This invention relates to a system for longitudinally connecting two tubes. More particularly, this invention relates to such a system whereby one tube is telescopically received within another tube and the two tubes are connected by a fastening system without distorting the tubes.
It is oftentimes desirable to longitudinally, telescopically connect tubing to extend the overall length thereof while reducing the diameter thereof. Such is often done, for example, in the field of antennas where metallic, usually aluminum, tubes form antenna elements of varying lengths. Since these elements often extend for several feet, for wind resistance and other purposes, it is desirable that they are formed of a plurality of telescoping tubes such that the tips thereof are of a lesser diameter than the end where they originate from the antenna boom.
One problem with creating such extended tubing is that the tubes cannot be distorted at the point of their connection, as such would adversely effect the transmission characteristics of the antenna elements. Thus, merely bolting the two tubes together is not acceptable in that in order to obtain the tightness required for a good connection, the tubing would be permanently dimpled or otherwise distorted.
An attempted solution to the problem has been to provide a longitudinal slit in the tube of the larger diameter and then utilize a clamp to tighten the larger tube onto the smaller tube. However, not only is it costly to slit the tubing and provide the clamp, but also the slit itself can be an undesirable distortion, and, more importantly, it creates a stress point for product failure. In addition, since good, solid contact between the tubes is required, with these types of connections it is likely necessary to add a contact-enhancing, oxidation-inhibiting paste such as that sold under the registered trademark PENETROX(copyright). But even then, an antenna element so constructed is subject to twisting at the area of the clamp.
Thus, the need exists for a system to longitudinally connect tubing which creates a strong connection without distortions and without creating undue stress points, all at a reasonable cost.
It is thus an object of the present invention to provide a system for longitudinally connecting the ends of telescoping tubes without distorting the tubes.
It is another object of the present invention to provide a system, as above, which provides a tight connection without the need for the application of contact-enhancing pastes or the like.
It is a further object of the present invention to provide a system, as above, in which there are no stress points created at the connection between the tubes.
It is an additional object of the present invention to provide a system, as above, which is inexpensive.
These and other objects of the present invention, as well as the advantages thereof over existing prior art forms, which will become apparent from the description to follow, are accomplished by the improvements hereinafter described and claimed.
In general, the subject invention includes a system for connecting two tubes with a fastening assembly. Each tube has a first hole aligned with the first hole of the other tube, which holes are opposed to aligned smaller second holes of each tube. The fastening assembly includes a fastening device having a head at one end and a threaded shaft at the other end. An enlarged sleeve is positioned between the head and the threaded end, the sleeve being smaller than the first holes but larger than the second holes. The sleeve can thereby pass through the aligned first holes of the tubes and the threaded shaft can pass through the aligned second holes of the tubes. A nut is received on the threaded shaft such that upon tightening of the nut on the shaft the sleeve engages one of the tubes to force it against the other of the tubes.
In accordance with another aspect of the present invention, a method of telescopically connecting a first tube to a second tube includes the steps of creating a first hole in each tube, and creating a second hole in each tube opposed to the first hole. The first holes are larger than the second holes. The first tube is inserted into the second tube. The first holes of the tubes are then aligned with each other and the second holes of the tubes are likewise aligned with each other. A fastener assembly having a threaded end and an enlarged sleeve is inserted through the first holes, and the threaded end is inserted through the second holes. A nut is tightened on the threaded end so that the sleeve clamps the tubes at the area of the second holes.